Questions

Passivity of iron is due to formation of an extremely thin and impervious film of ferrosoferric oxide Fe3O4on the surface of iron. Chromic acid, being a powerful oxidising agent (like nitric acid ) renders iron passive. 

DNA replication is the biological process of producing two identical replicas of DNA from one original DNA molecule. DNA replication occurs in all living organisms acting as the basis for biological inheritance. Complementary base pairing helps prevent errors in DNA replication.

India has acquired the top position among 30 developing countries on ease of doing business at the 2017 A.T. Kearney Global Retail Development Index (GRDI). The 2017 GRDI titled “The Age of Focus” ranked China at second place, followed by Malaysia, Turkey, United Arab Emirates (UAE) and Vietnam. The 16th edition of GRDI ranked top 30 developing countries for retail investment worldwide and analyzed 25 macroeconomic and retail-specific variables to help retailers devise successful global strategies to identify emerging market investment opportunities.

The other answers could be accurate in specific situations, but their role alone does not meet the keyb criterion of being "external" to the project team. Answers A, B, and D are incorrect because these individuals are not external to the project.

The rungs or the sides of the DNA ladder is made of Deoxyribose, which is a pentose, and a phosphate group are the two molecules together form the two sides of the DNA i.e, A sugar (deoxyribose) and a phosphate.